Data integrity is a major concern wherever data is to be transfered within a system. For instance, in communication networks data sent from an originating source terminal to a destination terminal may flow through a network including several intermediate nodes, over paths including several physical links.
Said data may be altered anywhere along its path and one should be able to detect alteration and discard the corresponding data.
In networks wherein HDLC or SDLC data packing techniques (both herein refered to as HDLC) are used, each data frame is provided with a data dependent frame check sequence (FCS) made to enable checking data integrity throughout the data path. After each data modification, the FCS should normally be updated.
The FCS sequence generation is performed through polynomial division operations adding to the system data handling and processing load. Methods for simplifying FCS updating operations are of great interest.
In several applications, like for instance in communication networks, the transmitted message frame includes information data and a so called header embedded into the frame and made to help the transmitted frame find its way within the network. This routing data may be modified throughout the network, and therefore the corresponding frame FCS needs be updated, accordingly.
In some instances the header modifications are limited to a predetermined section of the header being simply inserted or deleted.
One object of this invention is to provide a method for optimizing the FCS updating process for a frame a section of which is to be deleted or inserted somewhere along the frame path within the system, without altering the FCS checking efficiency.
This and other objects, characteristics and advantages of the present invention will be explained in the following, with reference to the attached drawings.